A cylinder-direct injection engine that injects fuel directly into a cylinder from a fuel injector has been known. In the engine of this type, there is a period in which a part of fuel injected from the fuel injector is adhered to an opened intake valve. This period is referred to as “interference period”, hereinafter. When injection fuel is adhered to the intake valve, a required amount of fuel cannot be supplied into the cylinder.
For that reason, for example, JP-A-2007-291887 discloses an injection period in which fuel is injected from the fuel injector is changed to avoid the interference period. Specifically, the injection period is divided into a front and a back of the interference period. Alternatively, the overall injection period moves behind the interference period. Both of those techniques derive from an idea that a portion of the injection period which overlaps with the interference period moves behind the interference period.
In the above related art, the fuel injection is not implemented in the interference period. For that reason, there is a high possibility that a larger amount of fuel must be injected after the termination of the interference period.
The fuel injection into the cylinder needs to be implemented within a given injectable period, and when a period (hereinafter referred to as “margin period”) from the termination time of the interference period to the termination time of the injectable period is shorter, a fuel injection for the avoided interference period cannot be implemented. In general, the interference period and the injectable period are determined according to a crank angle (rotation angle position of a crank shaft), in other words, intervals from one crank angle to another crank angle. Therefore, the margin period is shorter as an engine speed is higher. Hence, the above related art is more difficult to realize as the engine speed is higher.